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Water Supply in a Warming World

By Justin Gillis November 12, 2012 3:07 pmNovember 12, 2012 3:07 pm

Associated PressWomen en route to a water collection point near Ngara, Tanzania.

More than anything else, climate change is a water problem. Scientists expect more coastal flooding and possibly more inland flooding. They expect higher temperatures and greater evaporation to deplete water resources, creating risks for the food supply. They believe sea-level rise will eventually render some regions uninhabitable.

But a new paper published on Sunday in the journal Nature Climate Change suggests that the outlook on fresh water may not be entirely bad.

In many places around the world, groundwater is the most important source of local water supplies. And the new analysis, by Richard G. Taylor of University College London and a half-dozen other scientists, found that the more intense rainfall expected in many parts of the world as a result of climate change may help to recharge the aquifers that supply groundwater.

Their analysis is based on a 55-year record compiled in Tanzania that allowed them to study the relationship between groundwater recharge and rainfall. Their basic finding was that a disproportionate share of the recharge came from heavy storms.
This makes intuitive sense — presumably, it’s the heaviest rains that are able to saturate the surface and send water deeper underground rather than have it all evaporate once a storm has passed.

Some evidence suggests the same pattern holds true in other places, including the American Southwest. But this issue has not been well studied in most parts of the world. It will be interesting to see if other scientists can confirm the Taylor group’s findings and extend them beyond the tropics.

Since an intensification of rainfall is one of the most confident predictions scientists make about global warming, proof that this pattern applies worldwide would suggest that improved groundwater availability may help us offset some of the ill effects of climate change.

A summary of the paper is available here, and those with access to Nature Climate Change can click through to the full paper.

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